Nato has announced its biggest military call-up in decades with 90,000 troops preparing for global conflict as a top chief urges civilians and governments to brace for an all-out war.
A total of 20,000 British troops will be deployed as part of a test of their ability to engage in conflict.
Steadfast Defender will start next week until May and will see units from all 31 Nato member countries.
Following a series of meetings between national defence chiefs, Nato's Supreme Allied Commander Europe, US General Christopher Cavoli announced plans yesterday.
Nato has announced its biggest global military call-up in decades with 90,000 troops preparing for global conflict
Reuters
He said: "The Alliance will demonstrate its ability to reinforce the Euro-Atlantic area by a transatlantic movement of forces from North America."
The UK will send 20,000 troops, the Royal Navy's two new aircraft carriers and eight warships.
On Monday, Defence Secretary Grant Shapps said all three Armed Forces will be deployed to the drill.
It comes amid heightened concerns of huge global conflict.
Admiral Rob Bauer, the chairman of NATO's Military Committee said forces are bracing for a war with Russia in the next two decades.
He said: "We have to realise it's not a given that we are in peace. And that's why we [NATO forces] have the plans, that's why we are preparing for a conflict with Russia.
LATEST DEVELOPMENTS:
"We need public and private actors to change their mindset for an era in which everything was plannable, foreseeable, controllable and focused on efficiency to an era in which anything can happen at any time. An era in which we need to expect the unexpected."
The exercises are thought to be in preparation for a possible challenge from Russia.
A leaked military plan unveiled potential plans by Vladimir Putin to bring the West on the verge of world war.
The proposals give details of a possible "path to conflict" which reaches breaking point during the summer of 2025 on "Day X".
Earlier this week, the UK announced it would be sending a further £2.5billion support package to Ukraine.
The exercises are thought to be in preparation for a possible challenge from Russia
ReutersSteadfast Defender will also see 12,000 German soldiers called in, along with 3,000 vehicles and 30 aircraft.
It has been reported that the drill could cause a Russian attack on NATO territory.
This would trigger Article 5, which states that if any Nato country is attacked, all other alliance countries will mobilise to defend it.